Broken exhaust manifold bolt in cylinder head

Hi everyone!

I’ve barely been able to touch the bronco over the last 2 months (we’re opening a business so my only free time is sleep). But today is my birthday and that was enough to feel comfortable taking the day off and working on the fuel injection upgrade! No need for Bday wishes - just getting to do what I want today was good wishes enough.

Basically my whole day has been removing the manifolds and cleaning the surface of the cylinder head. I spent hours on it and I still don’t think it’s fully clean. I’m not sure if you can tell from the pics below, but I thought it was clean enough to try putting on the new manifolds.

And then trouble. It looks like the bolt for the front-most bolt hole is broken without any extension out of the hole. All the other bolts came out without issue and I didn’t remove a bolt there so it must have been running like that for some time.

Any recommendations on how to remove it? I’m thinking drilling it out, but I’m sure there a preferred way on the 300.

When you do drill it out use reverse rotating bits this way if it comes loose when drilling it will back out.
The hardest part will be drilling it in the center, start small and work up in size.

Maybe drill it out a little and spray it and let it sit a day or 2 to work in.
Being on the end it looks like you could also use heat on the head to expand that area around the broken bolt. Maybe heat & let it cool a few times before using the EZ out on it.
Dave ----

I was planning on using a punch to get a good center start. Not sure. Never really tried heating before, but I’m willing to try it. Just torch it around the bolt, then be ready to use the extractor?

FuzzFace2 wrote

When you do drill it out use reverse rotating bits this way if it comes loose when drilling it will back out.
The hardest part will be drilling it in the center, start small and work up in size.

Maybe drill it out a little and spray it and let it sit a day or 2 to work in.
Being on the end it looks like you could also use heat on the head to expand that area around the broken bolt. Maybe heat & let it cool a few times before using the EZ out on it.
Dave ----

Bummer! And on your B-Day too....sorry! Drilling it out is the way to go, but you need to be on center and drill at the appropriate angle of the bolt. I'd go with Dave's recommendation and try the reverse drill bit. You might get lucky, as drilling it will take some pressure off the threads. I'd PB Blast the thing, drill, heat it, and try with an easy out. Be advised you do not want to break that easy out extractor in the head, as you will likely be pulling the head and taking it to a machine shop for removal. If you feel like your putting too much pressure on the extractor, I'd step drill it to the appropriate tap drill size and use a tap to recut the treads. If you get off center with your initial drill bit, you'll need a heli-coil kit. Happy B-Day!  

If it was already broken off, you might be able to weld a nut to the stud and pull it that way. The heat from the welding can help loosen it too.

Otherwise, as mentioned previously, left handed bits are your friend. You can try a screw extractor after drilling it, but they sometimes don't work the best due to the spiral wedge expanding the stud. It all has to do with how stuck the stud is.

ratdude747 wrote

If it was already broken off, you might be able to weld a nut to the stud and pull it that way. The heat from the welding can help loosen it too.

Otherwise, as mentioned previously, left handed bits are your friend. You can try a screw extractor after drilling it, but they sometimes don't work the best due to the spiral wedge expanding the stud. It all has to do with how stuck the stud is.

I did think of welding a nut on to what might be left but it looks like the stud is below the head surface and would be hard to weld to just the stud and not the head and why I did not say anything about welding a nut on it.

Yes heating just the head, not the stud, should expand the head area keeping the stud cool and smaller and hopefully come right out.

As said be vary careful with the EZ out.
With the reverse drill you may get lucky and it will back out just drilling as maybe someone broke it going to tight?
Drill, a little penetrate oil and easy with the EZ out if it does not come out use heat on the head.
Go easy again on the EZ out. May want to do the heat, try, cool, try, heat, etc. a few times as the heating & cooling can break if free too.
Dave ----

Yeah, it’s definitely too deep in there to weld to. I’ve never torched anything before, but I suppose there has to be a first time and I’d much rather do that than take the head off... Thanks for the advice all. I’ll keep you updated.

Any note on how clean the face looks? I’m using a gasket so I’m hoping that helps.

FuzzFace2 wrote

ratdude747 wrote

If it was already broken off, you might be able to weld a nut to the stud and pull it that way. The heat from the welding can help loosen it too.

Otherwise, as mentioned previously, left handed bits are your friend. You can try a screw extractor after drilling it, but they sometimes don't work the best due to the spiral wedge expanding the stud. It all has to do with how stuck the stud is.

I did think of welding a nut on to what might be left but it looks like the stud is below the head surface and would be hard to weld to just the stud and not the head and why I did not say anything about welding a nut on it.

Yes heating just the head, not the stud, should expand the head area keeping the stud cool and smaller and hopefully come right out.

As said be vary careful with the EZ out.
With the reverse drill you may get lucky and it will back out just drilling as maybe someone broke it going to tight?
Drill, a little penetrate oil and easy with the EZ out if it does not come out use heat on the head.
Go easy again on the EZ out. May want to do the heat, try, cool, try, heat, etc. a few times as the heating & cooling can break if free too.
Dave ----

It looks like around the intake ports could use a little more cleaning in my book but other wise looks good.
Dave ----

Well I got a torch and all the fixings to get this out and I’m afraid I’m drilling a bit low. Should I go with a bigger bit now?

Also, I really have no concept of how long I should be torching for.

Yes, you are too low.  I'd use the same bit and angle it up, meaning drill from lower than your divot and aim up.  Then, after you've gone in maybe 1/8", slowly bring your drill up to horizontal.  But SLOWLY or you'll break your bit and then you have to fish the really hard drill bit out.  That should get you close to center.

Then drill in as far as you dare go before going to the next sized bit, and then only go up maybe 1/16" at a time.

Are you going to use EZOuts or what?  If you get really close to the center you can drill it out until you start to see the threads of the head showing, and then you can peel the bolt's metal out of the threads.

But if you are using EZOuts or somesuch you can drill it out until your EZOut will fit.  And that 's when you need the heat.  And depending on what torch you have, you can't get that head too hot.  MAP gas or propane just won't get it too hot.  Heat it and then chill it with something like PB Blaster.  Heat/cool.  You are trying to cause the two different metals to cool differently and break the bond.

You need to get that hole as centered as possable. That hole needs to be drilled all of the way through the bolt to brake the suction and to make it where you can spray some PB blaster or WD40 or what ever into it.

Now you are ready to heat the front edge of the head, not the bolt, the head. Heat it till the head starts to look a little blue. Stick in your easy out and back the bolt out, dont stop turning on it untill it is all of the way out.

Thanks gents! I’ll keep trying. I am using a reverse drill and planning on using an easy out.

All that's been said so far is right on the money.
As far as surface cleanliness goes - that looks fine.

Remember - DO NOT put a gasket between the exhaust manifold and the head! Make sure that the manifold is flat the full length, have it surfaced if necessary. Put a film of graphited grease on the face of the manifold before you bolt 'er on.

I’m using an Offy intake and switching to EFI Exhaust. Everything I’ve read says to use the gasket with the offset layer so that the washer matches up. Is there a reason not to go that route?

Using a gasket on a full length (carbed) manifold will definitely cause the manifold to warp and crack. The EFI manifolds aren't as bad, but they still run hotter if you use gaskets. We never put exhaust gaskets on anything with iron heads for this reason - the cylinder head acts as a heat sink for the manifold and keeps it cooler.

Very interesting! I can see the thought behind that. I wonder if separating the two gaskets will still give me the same offset. I’ll have to play with that.

On factory manifolds, the exhaust manifold has a thicker flange for this reason. Back in the 80's, Ford engineering did a lot of testing to prove this, as we were having chronic failures with tightening emissions and higher exhaust temperatures.

Ford discontinued using gaskets on almost all engines with iron heads.

So, we gotta know - how's the extraction going??

Great question. I’m about to go do it literally right now. I should live stream it.

I think good news. I just drilled through the bolt and there a good 3/4 of inch on the other side that isn’t all the way in. Looks like they got most of the way out and then it broke. Just sprayed some on blaster in the hole. I’m going to let it sit for 30 minutes and then hit it with heat. Spray some PB on it to cool and then use the easy out. Let’s see if that does it.